Experimental Investigations of the Weathering of Suspended Sediment by Alpine Glacial Meltwater

Abstract

The magnitude and processes of solute acquisition by dilute meltwater in contact with suspended sediment in the channelized component of the hydroglacial system have been investigated through a suite of controlled laboratory experiments. Constrained by field data from Haut Glacier d'Arolla, Valais, Switzerland the effects of the water to rock ratio, particle size, crushing, repeated wetting and the availability of protons on the rate of solute acquisition are demonstrated. These 'free-drift' experiments suggest that the rock flour is extremely geochemically reactive and that dilute quickflow waters are certain to acquire solute from suspended sediment. These data have important implications for hydrological interpretations based on the solute content of glacial meltwater, mixing model calculations, geochemical denudation rates and solute provenance studies.

Modelling of dripwater hydrology and hydrogeochemistry in a weakly karstified aquifer (Bath, UK): Implications for climate change studies

“…Brown et al (1996) focused on the occurrence of post-mixing chemical reactions as a barrier to interpretation of sources, but in our case, calcite precipitation has been recognized and explicitly allowed for in the model. The more fundamental problem for the linear systems approach is that of fluid interchange between fissures and matrix.…”

The effect of warming climate on nutrient and solute export from the Greenland Ice Sheet

“…Glaciers effectively fracture and grind bedrock into high surface area, highly reactive, clay and silt sized particles, some of which are transported in runoff as suspended material (Gurnell and Clark, 1987;Brown et al, 1996). By using data derived from the labile nutrients in the 2012 suspended material (n > 25), we estimated the range of nutrient concentrations associated with the particulate fraction (Table 1; Fig.…”

“…Particulates from meltwater are extremely fine, e.g., >95 % of particles can be <32 μm in size (Brown et al, 1996), so surface area is high and nutrient transport in the buoyant, fresh water plumes in near coastal regions is likely to be significant. Evidence from recent polar studies shows that particle borne nutrients are carried far offshore (Schroth et al, 2014;Wehrmann et al, 2014) and nutrients deposited with glacial sediments in fjords can be resuspended in the water column (Wehrmann et al, 2014).…”

Suspended sediment flux downstream of the retreating Castle Creek Glacier, Cariboo Mountains, British Columbia.

“…rock flour in glacial meltwater) is the chemically active portion of the solid load transported by a river and is an important vector for the transfer and fate of nutrients and contaminants through both terrestrial and aquatic ecosystems (Brown et al 1996;Owens et al 2005). For fluvial geomorphologists, developing a suspended sediment budget that quantifies the nature, importance and interaction between sediment production, mobilization, transport, storage and yield is a precursor to developing effective sediment management and control strategies aimed at reducing diffuse or point source pollution by fine sediment (Slaymaker 2003;Hodson et al 2004;Owens 2005;Walling 2005;Walling and Collins 2008).…”

“…• fine sediment < 63 pm (silts and clays) are the chemically active component of the solid sediment load; they can transport and store nutrients and contaminants (Brown et al 1996;Dirszowsky 2004;Hodson et al 2004;Owens et al 2005;Walling 2005;Hodson et al 2008;Haritashya et al 2010);…”